projects / apple / xnu.git / blame
| Commit | Line | Data |
|---|---|---|
| 1c79356b A |
1 | /* |
| 2 | * Copyright (c) 2000 Apple Computer, Inc. All rights reserved. | |
| 3 | * | |
| 4 | * @APPLE_LICENSE_HEADER_START@ | |
| 5 | * | |
| e5568f75 A |
6 | * The contents of this file constitute Original Code as defined in and |
| 7 | * are subject to the Apple Public Source License Version 1.1 (the | |
| 8 | * "License"). You may not use this file except in compliance with the | |
| 9 | * License. Please obtain a copy of the License at | |
| 10 | * http://www.apple.com/publicsource and read it before using this file. | |
| 1c79356b | 11 | * |
| e5568f75 A |
12 | * This Original Code and all software distributed under the License are |
| 13 | * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER | |
| 1c79356b A |
14 | * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, |
| 15 | * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, | |
| e5568f75 A |
16 | * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT. Please see the |
| 17 | * License for the specific language governing rights and limitations | |
| 18 | * under the License. | |
| 1c79356b A |
19 | * |
| 20 | * @APPLE_LICENSE_HEADER_END@ | |
| 21 | */ | |
| 22 | ||
| 23 | #;************************************************************************** | |
| 24 | #;* Boolean OSCompareAndSwap(SInt32 oldValue, SInt32 newValue, SInt32 * ptr) * | |
| 25 | #;************************************************************************** | |
| 26 | ||
| 27 | .globl _OSCompareAndSwap | |
| 28 | ||
| 29 | _OSCompareAndSwap: | |
| 30 | #; this is _lame_, the project will not currently accept asm code that | |
| 31 | #; requires anything beyond a 386, but that chip: | |
| 32 | #; - does not support MP | |
| 33 | #; - does not support the cmpxchgl instruction | |
| 34 | #; - does not support the lock meta-instruction | |
| 35 | #; so what is a poor guy to do? comment it out... | |
| 36 | pushl %edi | |
| 37 | pushl %esi | |
| 38 | movl 0+8+4(%esp),%eax #; oldValue | |
| 39 | movl 4+8+4(%esp),%edi #; newValue | |
| 40 | movl 8+8+4(%esp),%esi #; ptr | |
| 41 | lock | |
| 42 | cmpxchgl %edi,0(%esi) #; CAS (eax is an implicit operand) | |
| 43 | sete %al #; did CAS succeed? (TZ=1) | |
| 44 | andl $0x000000ff,%eax #; clear out the high bytes (has to be an easier way...) | |
| 45 | popl %esi | |
| 46 | popl %edi | |
| 47 | ret | |
| 48 |